A bi-fuel delivery system is understood to be any engine system that is capable of operating on two different types of fuel. Conversion from a mono-fuel system, such as a diesel fuel combustion engine commonly found in heavy-duty trucks and buses sold by large-scale manufacturers of such vehicles, to a bi-fuel system is advantageous because it typically results in the reduction of total fuel costs and lower vehicle emissions. There are, however, several challenges to converting a mono-fuel system into a bi-fuel system. In a standard, OEM configuration fuel system for an internal combustion engine, known in the art, the fuel systems are arranged for the use of only one type of fuel. For production efficiency, the components of the standard fuel delivery system are not manufactured with any intention for the system to contain or handle more than one type of fuel. Additionally, due to ever increasingly cramped engine compartments, retrofitting and adding new or modified components to a fuel system has become increasingly challenging. As a result, there is a need for reusing/repurposing as many OEM components as possible to allow for the installation of a bi-fuel delivery system on a cost-effective basis.
For compression ignition engines that are designed to run on diesel fuel, the fuel system generally has a diesel fuel tank, a fuel strainer, a fuel filter/water separator, and fuel lift pump that pressurizes the diesel fuel before it enters the engine via a fuel rail inlet port. These components are all designed without the intention to operate in a bi-fuel system environment, and as the present invention shows, these components require substantial modification and repurposing to run in the bi-fuel environment. One particular concern when adapting a system to run in a bi-fuel environment is minimizing cross contamination of the fuels to maximize the efficiency of how each fuel burns in the engine. As a result, converting a mono-fuel system to a bi-fuel system requires substantial repurposing and custom modification in order for the system to run in a fuel efficient manner.